diff --git a/Source/cmCacheManager.cxx b/Source/cmCacheManager.cxx
index d3d8f3fb3..9e0064e5d 100644
--- a/Source/cmCacheManager.cxx
+++ b/Source/cmCacheManager.cxx
@@ -930,7 +930,7 @@ bool cmCacheManager::NeedCacheCompatibility(int major, int minor)
 
   // Compatibility is needed if the cache version is equal to or lower
   // than the given version.
-  unsigned int actual_compat =
+  cmIML_INT_uint64_t actual_compat =
     CMake_VERSION_ENCODE(this->CacheMajorVersion, this->CacheMinorVersion, 0);
   return (actual_compat &&
           actual_compat <= CMake_VERSION_ENCODE(major, minor, 0));
diff --git a/Source/cmFindPackageCommand.h b/Source/cmFindPackageCommand.h
index 7ceebb266..0d80e48e7 100644
--- a/Source/cmFindPackageCommand.h
+++ b/Source/cmFindPackageCommand.h
@@ -114,7 +114,7 @@ private:
   unsigned int VersionFoundPatch;
   unsigned int VersionFoundTweak;
   unsigned int VersionFoundCount;
-  unsigned int RequiredCMakeVersion;
+  cmIML_INT_uint64_t RequiredCMakeVersion;
   bool Quiet;
   bool Required;
   bool UseConfigFiles;
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index a2a66aeb4..b8b703581 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -3345,7 +3345,7 @@ cmLocalGenerator::GetTargetDirectory(cmTarget const&) const
 }
 
 //----------------------------------------------------------------------------
-unsigned int cmLocalGenerator::GetBackwardsCompatibility()
+cmIML_INT_uint64_t cmLocalGenerator::GetBackwardsCompatibility()
 {
   // The computed version may change until the project is fully
   // configured.
@@ -3398,7 +3398,7 @@ bool cmLocalGenerator::NeedBackwardsCompatibility_2_4()
 
   // Compatibility is needed if CMAKE_BACKWARDS_COMPATIBILITY is set
   // equal to or lower than the given version.
-  unsigned int actual_compat = this->GetBackwardsCompatibility();
+  cmIML_INT_uint64_t actual_compat = this->GetBackwardsCompatibility();
   return (actual_compat &&
           actual_compat <= CMake_VERSION_ENCODE(2, 4, 255));
 }
diff --git a/Source/cmLocalGenerator.h b/Source/cmLocalGenerator.h
index ad662d58c..97648138a 100644
--- a/Source/cmLocalGenerator.h
+++ b/Source/cmLocalGenerator.h
@@ -321,7 +321,7 @@ public:
    *
    * and is monotonically increasing with the CMake version.
    */
-  unsigned int GetBackwardsCompatibility();
+  cmIML_INT_uint64_t GetBackwardsCompatibility();
 
   /**
    * Test whether compatibility is set to a given version or lower.
@@ -460,7 +460,7 @@ protected:
   bool RelativePathsConfigured;
   bool PathConversionsSetup;
 
-  unsigned int BackwardsCompatibility;
+  cmIML_INT_uint64_t BackwardsCompatibility;
   bool BackwardsCompatibilityFinal;
 private:
   std::string ConvertToOutputForExistingCommon(const char* remote,
diff --git a/Source/cmVersion.h b/Source/cmVersion.h
index e31352476..0ab639051 100644
--- a/Source/cmVersion.h
+++ b/Source/cmVersion.h
@@ -32,8 +32,13 @@ public:
   static const char* GetCMakeVersion();
 };
 
+/* Encode with room for up to 1000 minor releases between major releases
+   and to encode dates until the year 10000 in the patch level.  */
+#define CMake_VERSION_ENCODE__BASE cmIML_INT_UINT64_C(100000000)
 #define CMake_VERSION_ENCODE(major, minor, patch) \
-  ((major)*0x10000u + (minor)*0x100u + (patch))
+  ((((major) * 1000u) * CMake_VERSION_ENCODE__BASE) + \
+   (((minor) % 1000u) * CMake_VERSION_ENCODE__BASE) + \
+   (((patch)          % CMake_VERSION_ENCODE__BASE)))
 
 #endif